Are unlimited data plans really unlimited?

Yes, unlimited data plans don’t have a limit on the amount of data you can use — your data won’t turn off no matter how much you use.  

But the catch is they typically do not offer unlimited premium, high-speed data. Most plans have a cap saying how much premium data you get before your data may be slowed.  

In other words, don't read "unlimited" to mean "always at the highest speed" unless a phone plan specifically promises no slowing.

What does ‘unlimited data’ mean? 

An unlimited data plan gives you continuous access to data throughout your billing period. Some or all of it is premium data — data that gets a higher level of network access so it’s faster than others.  

There are two kinds of plans:  

• Capped unlimited data plans: These set a limit on how much premium data you can use, maybe 35GB, 50GB or even 100GB. After that, you still have data access, but your speeds may be slowed until the next billing period. 
• Uncapped unlimited data plans: There’s virtually no limit to how much premium data you can use. Providers usually have a fair-use policy on when heavy data users may be slowed, but it tends to be so high that few people are affected. For example, Verizon says customers in the top 0.5% of data usage may be slowed until the next billing period.  

Slowing can happen in two different ways: deprioritization or throttling.  

What is deprioritized data?  

Mobile service providers have to organize the traffic on their networks to manage the load when demand is high. They do that by giving different users different priority levels. Users with better priority will have faster speeds in high-demand situations like crowded areas or when many people are trying to use mobile data.  

But keep in mind, deprioritization only affects speeds temporarily, while the network is busy. So even if you’re on a cheaper plan that gets lower priority during congestion, you won’t necessarily see slowing all the time. 

How does data deprioritization work? 

Network operators assign different priority rankings to traffic on their cell networks. Higher priority traffic gets their data requests handled first, while deprioritized has to wait in line behind them and so might see slower response. Generally, the priority ranking looks like this:  

1. Best speeds: Unlimited postpaid plans from a mobile network operator (AT&T, Boost, T-Mobile, Verizon). 
2. Next-best speeds: Unlimited prepaid plans from a network operator or one of the secondary brands it owns, like Cricket (owned by AT&T), Visible (Verizon), and Metro by T-Mobile.  
3. Likeliest to be slowed: Unlimited prepaid plans from a mobile virtual network operator (MVNO). These are providers like US Mobile, Consumer Cellular, Straight Talk, etc. who don’t have their own cellular network but lease space from the network operators. 

Not coincidentally, that’s also how plan pricing tends to go: Postpaid plans are more expensive than prepaid plans from network operators, which in turn are more expensive than prepaid plans from MVNOs. If you want your data to be prioritized, you generally have to pay more for your plan.   

What is data throttling?  

Data throttling, on the other hand, isn’t a temporary slowing. After you’ve used the amount of premium data your plan gives you, your data may be slowed until the next billing cycle starts regardless of network congestion.  

Throttling is more common on prepaid plans. For example, Boost Mobile’s top plan, Unlimited Premium, gives you 50GB of premium data. After you use that, your data speeds may be slowed for the rest of the month. But it can happen with postpaid plans, too, usually on the lowest-price offerings. For example, T-Mobile’s Essentials plan also notes that speeds may be slowed after 50GB.  

Hotspot data can be deprioritized or throttled, too 

Mobile hotspot data also is subject to caps, and they’re typically lower than the overall data allowance on an unlimited plan. For example, Verizon’s postpaid Unlimited Plus plan specifies 30GB premium mobile hotspot data.

When choosing a plan, check its details to see how much premium hotspot data you get, and then look for phrases like “then slowed when busy” (you'll be deprioritized while the network is congested) or “then slowed to” plus a speed like 3G or 600 Kbps (you'll be throttled until the next billing cycle). 

If there’s no separate amount listed for mobile hotspot data, then any hotspot use comes from your overall data allowance. 

What happens when data is slowed?  

Depending on the speed your data is slowed to, you may not be able to do data-intensive things like stream video or play complex games. You can still do simpler things, like checking email or browsing websites.  

Here’s what you might see when your data is slowed:  

• Apps take longer to load, and if you have apps that run in the background that may further slow things down. 
• Video and music you’re trying to stream may pause to buffer and may be limited to a lower quality. For example, video may be in standard definition, not HD. 
• Games may get interrupted or react too slowly for reasonable playing experience. 
• Video calling may glitch or be interrupted. 
• Trying to send or download large files will take a long time or time out. 

If possible, switch to Wi-Fi to get faster internet access. Remember, mobile data and hotspot data are what’s subject to slowing — and on Wi-Fi, you’re not using those at all.  

Deprioritization and throttling both can mean slower performance on your phone, but they’re not the same thing. Here’s the difference between data deprioritization and throttling: 

Picking an unlimited data plan  

Take these steps when choosing your unlimited data plan to make sure it meets your data needs. 

1. Know how much data you really need 

While it’s tempting to figure the more data the better, buying more than you’ll actually use doesn’t make sense for your budget. Take a few minutes to understand how much data you actually use. It’s pretty easy to check usage on your phone, and if you haven’t had data before you can project how much to get based on the types of activities you want to do.  

2. When picking a phone plan, check the details 

When you're selecting a phone plan, check the details carefully to understand the amount of premium data and mobile hotspot data you get, and speeds you may be slowed to. Here’s where to look: 

Plan description: The amount of premium or priority data is often shown in the list of features, such as “35GB premium data.” If it simply says unlimited data, dig a little deeper. You may have to click on a link saying “view plan details” or read footnotes at the bottom of the web page. Look for a stated number of GB a plan allows before you’re subject to slowing.   

Terms & conditions: These tend to be long and tedious, but they often hold key details. Look for a link on the web page, oftentimes at the very bottom of the website. If you don’t want to read the entire document, try using the search function to seek out key terms like “GB,” “hotspot,” “speed,” and “slow.”  

Network management policy: This should be linked in the broadband facts sheet that’s required for each phone plan. The broadband facts include information on typical speeds provided with the plan, the data included in the monthly price, and a link to the network management policy. Again, this is a long document. Trying searching for “wireless” to see the part specific to cell plans or for “heavy” to find what heavy data users can expect.  

3. Consider building in some flexibility 

Know whether the provider you’re considering will let you trade up or down if the plan you choose isn’t right. Prepaid phone plans tend to have the most flexibility — because you’re not on a long-term contract, you’re free to change plan or provider at any time. Postpaid carriers typically let you trade up to a higher plan, but it’s trickier to trade down — especially if you financed a phone or are accumulating credits toward a phone upgrade. 

Before you commit to something, make sure you understand whether you can make changes and if there are any penalties.